US20210384801A1 - Rotor and electric motor including same - Google Patents
Rotor and electric motor including same Download PDFInfo
- Publication number
- US20210384801A1 US20210384801A1 US17/411,358 US202117411358A US2021384801A1 US 20210384801 A1 US20210384801 A1 US 20210384801A1 US 202117411358 A US202117411358 A US 202117411358A US 2021384801 A1 US2021384801 A1 US 2021384801A1
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- US
- United States
- Prior art keywords
- fluid
- rotor core
- rotary shaft
- rotor
- end ring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000012530 fluid Substances 0.000 claims abstract description 196
- 239000012809 cooling fluid Substances 0.000 claims abstract description 108
- 238000004891 communication Methods 0.000 claims abstract description 69
- 238000002347 injection Methods 0.000 claims abstract description 33
- 239000007924 injection Substances 0.000 claims abstract description 33
- 239000007921 spray Substances 0.000 claims description 76
- 238000001816 cooling Methods 0.000 description 27
- 230000004308 accommodation Effects 0.000 description 20
- 229910000976 Electrical steel Inorganic materials 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
- H02K9/193—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil with provision for replenishing the cooling medium; with means for preventing leakage of the cooling medium
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/32—Rotating parts of the magnetic circuit with channels or ducts for flow of cooling medium
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/18—Casings or enclosures characterised by the shape, form or construction thereof with ribs or fins for improving heat transfer
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/20—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
- H02K5/207—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium with openings in the casing specially adapted for ambient air
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/02—Arrangements for cooling or ventilating by ambient air flowing through the machine
- H02K9/04—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium
- H02K9/06—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium with fans or impellers driven by the machine shaft
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K9/00—Arrangements for cooling or ventilating
- H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2205/00—Specific aspects not provided for in the other groups of this subclass relating to casings, enclosures, supports
- H02K2205/09—Machines characterised by drain passages or by venting, breathing or pressure compensating means
Definitions
- the present disclosure relates to an electric motor that directly cools a shaft and a rotor using oil circulation.
- An electric vehicle may include an electric motor as a driving source for traveling the vehicle without exhaust gas.
- An electric motor may include a rotor and a stator, and the rotor may be rotatably provided inside the stator.
- the stator may include a stator coil wound around a stator core. When current flows along the stator coil to rotate the rotor, heat may be generated in the stator coil.
- cooling of heat generated in the electric motor may play an important role in achieving a smaller and more efficient electric motor.
- Motor cooling methods may include an indirect cooling method (water cooling) in which a channel for circulating cooling water is provided in a housing to indirectly cool a motor, and a direct cooling method (oil cooling) in which oil is sprayed onto a stator coil and the like to directly cool a motor.
- water cooling water cooling
- direct cooling method oil cooling
- the direct cooling method may have a high cooling efficiency and cooling performance, compared to the indirect cooling method using the cooling water.
- a fluid channel through which oil flows may be provided in a shaft and a rotor core. As the oil flows along the fluid channel, the rotor core and permanent magnets may be cooled.
- FIG. 1 is a conceptual view illustrating a movement path of oil in an electric motor of the related art.
- an oil channel 6 passing from a rotor core 3 to magnets 4 may be formed in the rotor core 3 axially in both directions of a shaft 2 , so that oil may be sprayed in the both directions through end plates 5 mounted on both ends of the rotor core 3 .
- the oil may be diverged and sprayed from the rotor core 3 axially in the both directions opposite to each other.
- a circulation flow rate at which the oil flows along the oil channel 6 may be slowed, and thereby the cooling performance of the oil may be deteriorated.
- the oil introduced through an oil inlet of the shaft 2 is filled in the oil channel 6 inside the rotor core 3 by centrifugal force, when the oil is sprayed in the both directions through center holes 7 formed through the both end plates 5 , respectively, the oil may be stagnated in the oil channel 6 formed between the two end plates 5 .
- the present disclosure describes an electric motor that can increase a circulation flow rate of oil and improve cooling performance of a shaft and a rotor by using oil circulation.
- the present disclosure also describes an electric motor that can increase a circulation flow rate of oil flowing along a fluid channel defined inside a shaft and a rotor core by fast rotating air around end plates to lower pressure of the air.
- a rotor includes a rotary shaft defining a first fluid channel configured to guide a cooling fluid, a rotor core that is configured to rotate about the rotary shaft, that includes a plurality of permanent magnets, and that defines a plurality of second fluid channels that are in fluid communication with the first fluid channel and configured to cool the plurality of permanent magnets by the cooling fluid, and a plurality of end rings that are respectively disposed at end portions of the rotor core and that define a plurality of spray holes that are in fluid communication with the plurality of second fluid channels and configured to spray the cooling fluid to an outside of the rotor core.
- Each end ring among the plurality of end rings includes a plurality of rotary fins that are disposed on an outer surface of the end ring and spaced apart from one another in a circumferential direction, where the plurality of rotary fins are configured to circulate, to the first fluid channel, the cooling fluid sprayed through the plurality of spray holes.
- each fin of the plurality of rotary fins can protrude from the outer surface of the end ring in an axial direction of the rotary shaft and has a curved shape that is curved from an inner end portion of the end ring to an outer end portion of the end ring in a radial direction, where the plurality of rotary fins are configured to cause air to rotate around the end ring.
- the plurality of end rings can include a first end ring disposed at a first end portion of the rotor core and a second end ring disposed at a second end portion of the rotor core, where the second end portion is spaced apart from the first end portion in an axial direction of the rotary shaft.
- the first end ring and the second end ring can be asymmetric with each other.
- the rotor core can further define a plurality of axial fluid channels that extend from a radially inner end portion of the rotor core, where the plurality of axial fluid channels are connected to and in fluid communication with the first fluid channel, and each of the plurality of return fluid channels can include a connection fluid channel that is connected to and in fluid communication with one of the plurality of axial fluid channels.
- the cooling fluid can be oil.
- each of the plurality of spray holes can be inclined with respect to an axial direction of the rotary shaft and extends toward an outside of one of the plurality of end rings.
- each of the plurality of injection fluid channels of the first end ring can face one of the plurality of return fluid channels of the second end ring in the axial direction.
- the rotor core and the plurality of permanent magnets can be configured to be cooled by the cooling fluid moving from the first fluid channel to the plurality of second fluid channels.
- the plurality of spray holes can be configured to spray the cooling fluid to a stator coil disposed outside the rotor core to thereby cool the stator coil.
- the rotor can include a plurality of paths configured to transfer the cooling fluid from the rotary shaft to the rotor core, where a number of the plurality of paths is equal to a number of poles of the plurality of permanent magnets.
- the rotary shaft can further define a plurality of communication holes that are connected to the rotor core, that are defined at a middle portion of the rotary shaft, and that extend in a radial direction of the rotary shaft.
- the plurality of communication holes can include a plurality of first communication holes defined through the first end portion of the rotary shaft, and a plurality of second communication holes defined through the second end portion of the rotary shaft, where each of the plurality of first communication holes is spaced apart from one of the plurality of second communication holes in the circumferential direction by a preset angle.
- an electric motor includes a housing, a stator that is disposed in the housing and includes a stator core and a stator coil wound around the stator core, a rotor including a rotary shaft, a rotor core disposed in the stator and configured to rotate about the rotary shaft, and a plurality of permanent magnets disposed at the rotor core, and a plurality of end rings respectively disposed at ends of the rotor core.
- the housing defines a plurality of spray nozzles therein that are configured to spray a cooling fluid to the stator coil and the stator core.
- the rotor defines a first fluid channel inside the rotary shaft, a plurality of second fluid channels inside the rotor core, where the plurality of second fluid channel are in contact with the plurality of permanent magnets, and a plurality of spray holes that are connected to and in fluid communication with the plurality of second fluid channels, where the plurality of spray holes extend obliquely through an outer circumferential portion of one of the plurality of end rings and are configured to spray the cooling fluid to an end portion of the stator coil.
- the first fluid channel, the plurality of second fluid channels, and the plurality of spray holes define a single-pass structure configured to guide the cooling fluid in a single direction.
- each end ring among the plurality of end rings can include a plurality of rotary fins that protrude from an outer surface of the end ring and that have a curved shape, where the plurality of rotary fins are configured to circulate, to the first fluid channel, the cooling fluid sprayed from the plurality of spray nozzles and the plurality of spray holes.
- the plurality of end rings can include a first end ring and a second end ring that are spaced apart from each other in the single direction.
- the plurality of second fluid channels are spaced apart from one another and extend parallel to the single direction.
- the rotary shaft can further define a plurality of communication holes that are connected to the rotor core and extend in a radial direction of the rotary shaft.
- the plurality of communication holes can include a plurality of first communication holes defined at a first end portion of the rotary shaft, and a plurality of second communication holes defined at a second end portion of the rotary shaft, where each of the plurality of first communication holes is spaced apart from one of the plurality of second communication holes in a circumferential direction of the rotary shaft by a preset angle.
- the electric motor can include a plurality of first pipes that extend from the plurality of first communication holes to the rotor core, and a plurality of second pipes that extend from the plurality of second communication holes to the rotor core, where a length of each of the plurality of first pipes is different from a length of each of the plurality of second pipes.
- a plurality of rotary fins can protrude from an outer surface of each end ring in a curved shape along a circumferential direction.
- air around spray holes of the end ring can flow rapidly, which can cause a pressure drop.
- a cooling fluid can flow from a first fluid channel of a rotary shaft into axial fluid channels and second fluid channels of the rotor core so as to be sprayed onto an inner circumferential surface of an end turn of a stator through a plurality of spray holes.
- the plurality of rotary fins can provide circulating power to the cooling fluid, so that the cooling fluid can move from the first fluid channel of the rotary shaft into the axial fluid channels and second fluid channels of the rotor core and easily circulate back to the first fluid channel of the rotary shaft through spray holes of the end ring, thereby increasing a circulation flow rate of the cooling fluid.
- a flow rate of the cooling fluid introduced into the rotary shaft can increase.
- circulating power of the cooling fluid can further be doubled.
- the cooling fluid can flow along each of a plurality of permanent magnets so as to uniformly cool down the permanent magnets for each polarity.
- a plurality of injection fluid channels and a plurality of return fluid channels can be alternately disposed in an inner surface of the end ring in a spaced manner along a circumferential direction, and the cooling fluid in the rotor core can move in the same single direction along the axial fluid channels and the second fluid channels so as to implement a single-pass structure. Accordingly, a flow rate and a circulation flow rate of the cooling fluid can increase, thereby improving cooling performance of the rotor and the stator.
- FIG. 1 is a conceptual view illustrating a movement path of oil in an electric motor of related art.
- FIG. 2 is a cross-sectional view illustrating an internal structure of an example electric motor.
- FIG. 3 is a conceptual view illustrating an example rotor of FIG. 2 .
- FIG. 4 is a conceptual view illustrating example end rings mounted to both ends of a rotor core in FIG. 3 .
- FIG. 5 is a conceptual view illustrating an example structure including a plurality of injection fluid channels and a plurality of return fluid channels that are alternately defined through each end ring in FIG. 4 .
- FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 3 .
- FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6 .
- FIG. 8 is a conceptual view illustrating an example of a movement path of oil.
- FIG. 9 shows a graph and a table comparing example flow rates of a cooling fluid into an inlet of a rotary shaft of an example electric motor with rotary fins and an electric motor without rotary fins.
- FIG. 10 is a conceptual view illustrating another example of a movement path of oil.
- FIG. 11 is a conceptual view illustrating an example of first and second paths of a cooling fluid transferred from a rotary shaft to a rotor core of FIG. 2 .
- FIG. 12 is a conceptual view taken along the line XII-XII in FIG. 11 illustrating an example structure in which first and second paths of a cooling fluid transferred in both directions from the rotary shaft to the rotor core, respectively, are defined with a phase difference from each other in a circumferential direction.
- FIG. 2 is a cross-sectional view illustrating an internal structure of an example electric motor
- FIG. 3 is a conceptual view illustrating an example rotor 130 of FIG. 2
- FIG. 4 is a conceptual view illustrating example end rings mounted to both ends of a rotor core 133 in FIG. 3
- FIG. 5 is a conceptual view illustrating an example structure in which a plurality of injection fluid channels 141 and a plurality of return fluid channels 142 are alternately defined through each end ring in FIG. 4
- FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 3
- FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6
- FIG. 8 is a conceptual view illustrating an example of a movement path of oil in accordance with the present disclosure.
- an electric motor can include a housing 100 , a housing cover, a stator 119 , and a rotor 130 .
- the housing 100 can have a cylindrical shape. An accommodation space can be defined inside the housing 100 .
- the stator 119 and the rotor 130 can be accommodated in the housing 100 .
- the housing cover can be provided on both ends of the housing 100 in a lengthwise direction to cover both end portions of the housing 100 .
- the housing cover can include a first housing cover 115 disposed on one end of the housing 100 and a second housing cover 117 disposed on another end of the housing 100 .
- a cooling fluid channel 110 in which a cooling fluid such as oil flows can be defined in the housing 100 .
- An inlet can be defined through an upper portion of the housing 100 , so that the cooling fluid can be injected into the housing 100 .
- a plurality of spray nozzles can be defined through the inside of the housing 100 in a thickness direction.
- the plurality of spray nozzles can be spaced apart from one another in a lengthwise direction of the housing 100 .
- One side of each of the plurality of spray nozzles can communicate with the cooling fluid channel 110 and another side of each of the plurality of spray nozzles can communicate with the accommodation space of the housing 100 .
- the plurality of spray nozzles can be defined perpendicularly downward or can be inclined. Some of the plurality of spray nozzles can be defined horizontally.
- First spray nozzles 111 defined horizontally among the plurality of spray nozzles can spray oil into the accommodation space toward the first housing cover 115
- second spray nozzles 112 defined to be inclined among the plurality of spray nozzles can spray oil into the accommodation space toward a bearing 118 .
- Third spray nozzles 113 defined perpendicularly downward among the plurality of spray nozzles can spray oil into the accommodation space toward an outer circumferential portion of an end turn 122 of the stator coil 121
- fourth spray nozzles 114 defined perpendicularly downward among the plurality of spray nozzles can spray oil into the accommodation space toward the stator core 120 .
- a cooling fluid such as oil can be sprayed onto the stator coil 121 , the stator core 120 , and the bearing 118 to cool the stator coil 121 , the stator core 120 , and the bearing 118 .
- a cover fluid channel 116 can be defined in the first housing cover 115 .
- One side of the cover fluid channel 116 can communicate with an accommodation hole in which oil sprayed from the first spray nozzles 111 , and a middle portion of the cover fluid channel 116 can communicate with an inside of one end portion of the rotary shaft 131 .
- the oil injected from the first spray nozzles 111 can be sprayed into the cover fluid channel 116 through the accommodation hole, and the oil flowing along the cover fluid channel 116 can flow into the one end portion of the rotary shaft 131 .
- the stator 119 can include a stator core 120 and a stator coil 121 .
- the stator core 120 can include a plurality of electrical steel sheets that are stacked.
- a rotor accommodation hole for accommodating the rotor 130 can be defined in a radial center of the stator core 120 .
- a plurality of slots and a plurality of teeth can be alternately disposed at an inner side of the stator core 12 in a circumferential direction.
- the plurality of slots can be defined through the stator core 120 in an axial direction.
- the stator coil 121 can be configured as a hairpin type.
- the plurality of stator coils 121 can be wound around the stator core 120 through the plurality of slots. End turns 122 that protrude from the slots to the outside of the stator core 120 can be disposed at both end portions of the stator coil 121 , respectively.
- the end turns 122 can be bent from the stator coil 121 at a preset angle and extend to an opposite side in a lengthwise direction of the stator core 120 .
- the rotor 130 can include a rotary shaft 131 , a rotor core 133 , permanent magnets 137 , and end rings.
- the rotary shaft 131 can have a first fluid channel 132 therein, such that a cooling fluid flows along the first fluid channel 132 .
- the first fluid channel 132 can extend in the axial direction.
- a plurality of communication holes 1310 can be defined through one side of the rotary shaft 131 in the radial direction.
- the plurality of communication holes 1310 can be configured to transfer the cooling fluid flowing along the first fluid channel 132 into the rotor core 133 .
- the plurality of communication holes 1310 can be disposed on the rotary shaft 131 to be spaced apart from one another in the circumferential direction.
- the plurality of communication holes 1310 can be disposed on a central portion of the rotary shaft 131 in a lengthwise direction of the rotary shaft 131 .
- the rotor core 133 can be mounted to the rotary shaft 131 to be rotatable together with the rotary shaft 131 .
- the rotor core 133 can have a cylindrical shape.
- the rotor core 133 can include a plurality of electrical steel sheets that are stacked.
- a rotary shaft accommodation hole for accommodating the rotary shaft 131 can be defined through the center of the rotor core 133 in the axial direction.
- a plurality of permanent magnet accommodation holes for accommodating a plurality of permanent magnets 137 can be defined in the rotor core 133 .
- a plurality of axial fluid channels 135 and a plurality of second fluid channels 136 through which the cooling fluid flows can be defined in the rotor core 133 .
- the plurality of axial fluid channels 135 can be defined in an inner end portion of the rotor core 133 in the radial direction.
- the plurality of axial fluid channels 135 can be spaced apart from one another in the circumferential direction.
- Each of the plurality of axial fluid channels 135 can extend along the axial direction of the rotor core 133 .
- the plurality of axial fluid channels 135 can communicate with the plurality of communication holes 1310 , such that the cooling fluid can move from the rotary shaft 131 to the rotor core 133 through the plurality of communication holes 1310 . Accordingly, the cooling fluid can directly cool down the rotor core 133 through heat exchange with the rotor core 133 .
- the plurality of second fluid channels 136 can surround the permanent magnets 137 such that the cooling fluid can be brought into contact with at least parts or portions of the permanent magnets 137 so as to cool down the permanent magnets 137 through heat conduction from the permanent magnets 137 .
- the plurality of second fluid channels 136 can be defined in an outer end portion of the rotor core 133 in the radial direction.
- the plurality of second fluid channels 136 can be spaced apart from one another in the circumferential direction.
- Each of the plurality of second fluid channels 136 can extend in a lengthwise direction of the rotor core 133 .
- the plurality of second fluid channels 136 can be parallel to the plurality of axial fluid channels 135 . However, the plurality of second fluid channels 136 can be connected respectively to the plurality of axial fluid channels 135 by inner fluid channels defined in an inner surface of the end ring. The plurality of second fluid channels 136 can be arranged in parallel, for example, in two rows.
- the cooling fluid can flow from the axial fluid channels 135 into the second fluid channels 136 to be brought into contact with the permanent magnets 137 , thereby cooling down the permanent magnets 137 through heat exchange with the permanent magnets 137 .
- the end rings can be coupled to cover both ends of the rotor core 133 , and can be mounted to the rotary shaft 131 to be rotatable together with the rotary shaft 131 .
- a rotary shaft accommodation hole can be defined through a center of each end ring.
- a plurality of spray holes (or injection holes) 140 can be defined through an outer circumferential portion of the end ring in a thickness direction. Each of the plurality of spray holes 140 can communicate with the plurality of second fluid channels 136 . The plurality of spray holes 140 can be spaced apart from one another in a circumferential direction of the end ring.
- the cooling fluid can be sprayed from the rotor core 133 into the accommodation space of the housing 100 through the plurality of spray holes 140 .
- Each of the plurality of spray holes 140 can be disposed at an inner side of the outer circumferential portion of each end ring to be inclined toward an inner circumferential surface of the end turn 122 of the stator coil 121 .
- the cooling fluid can be sprayed on the inner circumferential surface of the end turn 122 of the stator coil 121 through the plurality of spray holes 140 . Accordingly, a contact area of the stator coil 121 with the cooling fluid can be further expanded to the inner circumferential surface as well as the outer circumferential surface of the end turn 122 , thereby further improving the cooling performance by taking more heat from the stator coil 121 .
- a plurality of rotary fins 145 can protrude from an outer surface of each end ring in the axial direction, so as to rotate air around the end ring.
- Each of the plurality of rotary fins 145 can rotate together with the rotor core 133 centering on the rotary shaft 131 .
- Each of the plurality of rotary fins 145 can be disposed to be spaced apart from one another in the circumferential direction.
- Each of the plurality of rotary fins 145 can have a curved shape.
- Each of the plurality of rotary fins 145 can have an arcuate shape.
- the plurality of rotary fins 145 can be bent in the same direction as a rotating direction of the rotor core 133 .
- Outer end portions of the rotary fins 145 in the radial direction can be disposed adjacent to an outer circumferential portion of the end ring, and inner end portions of the rotary fins 145 can be disposed adjacent to the rotary shaft accommodation hole of the end ring.
- An interval between the outer end portions of the plurality of rotary fins 145 adjacent to each other in the circumferential direction can be wider than an interval between the inner end portions of the plurality of rotary fins 145 adjacent to each other in the circumferential direction.
- the outer end portions of the rotary fins 145 can be disposed adjacent to the spray holes 140 , such that air around an outer side of the spray holes 140 can be quickly moved. Accordingly, pressure can be lowered at the outer side of the spray holes 140 , which can facilitate circulation of the cooling fluid.
- a plurality of injection fluid channels 141 and a plurality of return fluid channels 142 can be disposed in an inner surface of each end ring.
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 can be alternately spaced apart from each other in the circumferential direction of the end ring.
- Each of the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 can be recessed in the inner surface of each end ring in the thickness direction.
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 can be defined to correspond to an arrangement shape of the permanent magnets 137 .
- the plurality of permanent magnets 137 can have a plate shape and can be arranged in an inverted triangle shape.
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 can be defined in an inverted triangular shape.
- the plurality of injection fluid channels 141 can communicate with the plurality of spray holes 140 , respectively.
- Each of the plurality of injection fluid channels 141 can be configured to connect the second fluid channel 136 and the spray hole 140 .
- the plurality of spray holes 140 can be disposed on an outer surface of each of the plurality of injection fluid channels 141 to be spaced apart from each other in the circumferential direction.
- the plurality of injection fluid channels 141 can temporarily collect and store the cooling fluid delivered from the second fluid channels 136 and distribute the cooling fluid into the plurality of spray holes 140 .
- the distributed cooling fluid can then be sprayed onto the end turn 122 through the plurality of spray holes 140 .
- the plurality of return fluid channels 142 can change a flowing direction of the cooling fluid transferred from the axial fluid channels 135 to return to the second fluid channels 136 .
- Each of the plurality of return fluid channels 142 can be provided with a connection fluid channel 143 at an inner side of the end ring in the radial direction.
- One side of the connection fluid channel 143 can communicate with the second fluid channel 136 and another side of the connection fluid channel 143 can communicate with the axial fluid channel 135 , such that the second fluid channel 136 and the axial fluid channel 135 can be connected to each other.
- the rotor core 133 can include a plurality of weight-reducing holes 134 disposed between the permanent magnet accommodation holes and the rotary shaft accommodation hole.
- the plurality of weight-reducing holes 134 can extend along the lengthwise direction of the rotor core 133 .
- the plurality of weight-reducing holes 134 can be spaced apart from the permanent magnet accommodation holes with a preset phase difference 8 in the circumferential direction.
- a plurality of weight-reducing grooves 144 can be defined at the inner surface of each end ring.
- the plurality of weight-reducing grooves 144 can have a shape corresponding to the plurality of weight-reducing holes 134 so as to communicate with the plurality of weight-reducing holes 134 in an overlapping manner along the axial direction.
- connection fluid channel 143 can communicate with the weight-reducing groove 144 .
- One side of the connection fluid channel 143 can connect the second fluid channel 136 and the weight-reducing groove 144
- another side of the connection fluid channel 143 can connect the weight-reducing groove 144 and the axial fluid channel 135 .
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 can be alternately arranged in the circumferential direction, so that the cooling fluid can be transferred from the rotary shaft 131 to the rotor core 133 through a single-pass structure.
- the single-pass structure means that the cooling fluid passes only once along the same path (or direction) through the axial fluid channels 135 and the second fluid channels 136 , which are the inner fluid channels of the rotor core 133 , from the rotary shaft 131 .
- Front and rear end portions of the rotary shaft 131 can be rotatably supported by bearings 118 .
- the bearings 118 can be mounted to the first housing cover 115 and the second housing cover 117 .
- a sealing cover can be mounted on the first housing cover 115 , to seal a gap between the first housing cover 115 and the first fluid channel 132 of the rotary shaft 131 .
- the end rings can include a first end ring 138 disposed on one end of the rotor core 133 facing the first housing cover 115 in the axial direction, and a second end ring 139 disposed on another end of the rotor core 133 facing the second housing cover 117 in the axial direction.
- first end ring 138 and the second end ring 139 can be asymmetric to each other.
- First rotary fins 1451 disposed on the outer surface of the first end ring 138 and second rotary fins 1452 disposed on the outer surface of the second end ring 139 can be curved in the same direction as the rotating direction of the rotor core 133 .
- the first rotary fins 1451 can be curved clockwise and rightward from inside to outside in the radial direction.
- the second rotary fins 1452 can be curved counterclockwise and leftward from the inside to the outside in the radial direction.
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 defined in the inner surface of the first end ring 138 and the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 defined in the inner surface of the second end ring 139 can be disposed in an alternating manner in the axial direction with a preset phase difference in the circumferential direction.
- the injection fluid channel 141 of the first end ring 138 and the return fluid channel 142 of the second end ring 139 can be disposed to face each other in the axial direction, and the injection fluid channel 141 of the first end ring 138 and the injection fluid channel 141 of the second end ring 139 can be alternately arranged in the axial direction.
- An inlet can be defined from one end portion of the rotary shaft 131 to be opened. Accordingly, a cooling fluid such as oil can be introduced into the first fluid channel 132 through the inlet of the rotary shaft 131 .
- the cooling fluid can be air.
- the cooling fluid can cool the rotary shaft 131 through heat exchange with the rotary shaft 131 while flowing along the first fluid channel 132 of the rotary shaft 131 .
- the cooling fluid can be delivered to the rotor core 133 through the communication hole 1310 connecting the rotary shaft 131 and the rotor core 133 .
- the number of paths along which the cooling fluid is transferred from the rotary shaft 131 to the rotor core 133 can be the same as the number of poles of the electric motor.
- the electric motor can have 6 poles, and six paths of the cooling fluid transmitted from the rotary shaft 131 to the rotor core 133 through the communication holes 1310 can be defined.
- the cooling fluid can be introduced into the first end ring 138 along the axial fluid channels 135 extending toward the first end ring 138 in the axial direction.
- connection fluid channels 143 connecting the first end ring 138 and the rotor core 133 can be defined in the inner surface of the first end ring 138 and extend radially to communicate with the axial fluid channels 135 .
- the cooling fluid can be introduced into the weight-reducing grooves 144 through the connection fluid channels 143 via the axial fluid channels 135 , temporarily stay in the weight-reducing grooves 144 , and then flow to the return fluid channels 142 through the connection fluid channels 143 again.
- the return fluid channels 142 can communicate with the second fluid channels 136 and switch a flowing direction of the cooling fluid such that the cooling fluid can flow from the first end ring 138 to the second end ring 139 in the axial direction.
- the cooling fluid can be introduced into the permanent magnet accommodation holes while flowing along the second fluid channels 136 , so as to cool down the permanent magnets 137 through heat exchange with the permanent magnets 137 .
- the cooling fluid can flow onto an inner surface of the second end ring 139 through the injection fluid channel 141 that connects the rotor core 133 and the second end ring 139 and faces the return fluid channel 142 of the first end ring 138 in the axial direction.
- the cooling fluid can be sprayed from the second end ring 139 into the accommodation space of the housing 100 through the plurality of spray holes 140 defined through the injection fluid channel 141 . At this time, the cooling fluid can be sprayed onto an inner circumferential surface of the end turn 122 through the plurality of spray holes 140 , thereby cooling down the stator coil 121 through heat exchange with the end turn 122 .
- the cooling fluid sprayed from the second end ring 139 can flow back into the rotary shaft 131 and circulate.
- the cooling fluid can be transferred from the rotary shaft 131 to the rotor core 133 .
- the cooling fluid inside the rotor core 133 can flow in the same single direction, that is, from the first end ring 138 to the second end ring 139 along the second fluid channels 136 , and be sprayed onto the inner circumferential surface of the end turn 122 , which protrudes from one end portion of the stator core 120 in the lengthwise direction, through the spray holes 140 of the second end ring 139 .
- the cooling fluid can flow through a single-pass structure.
- the number of paths that the cooling fluid is transmitted from the rotary shaft 131 to the rotor core 133 can be 6 paths, and the cooling fluid can radially move in the rotor core 133 independently for each polarity and move in a single pass for each polarity.
- a moving direction of the cooling fluid in the rotor core 133 can change from the first end ring 138 to the second end ring 139 or from the second end ring 139 to the first end ring 138 in an alternating manner whenever a position changes to an adjacent polarity in a circumferential direction.
- the plurality of rotary fins 145 can protrude from the outer surface of each end ring to be curved in the circumferential direction. As the plurality of rotary fins 145 rotate together with the rotor core 133 , air around the spray holes 140 of the end ring can flow fast to cause a pressure drop. Accordingly, the cooling fluid can flow from the first fluid channel 132 of the rotary shaft 131 to the axial fluid channels 135 and the second fluid channels 136 of the rotor core 133 so as to be sprayed onto the inner circumferential surface of the end turn 122 of the stator 119 through the plurality of spray holes 140 .
- the cooling fluid can move from the first fluid channel 132 of the rotary shaft 131 to the axial fluid channels 135 and the second fluid channels 136 of the rotor core 133 , so as to easily circulate from the spray holes 140 of the end ring back to the first fluid channel 132 of the rotary shaft 131 , thereby increasing a circulation flow rate of the cooling fluid.
- a flow rate of the cooling fluid flowing into the rotary shaft 131 can increase.
- the plurality of rotary fins 145 are disposed on each of the first end ring 138 and the second end ring 139 to be curved in the same direction as the rotating direction of the rotor core 133 , circulating power of the cooling fluid can be further doubled.
- the cooling fluid can flow to each of the plurality of permanent magnets 137 , so as to uniformly cool down the permanent magnets 137 for each polarity.
- the plurality of injection fluid channels 141 and the plurality of return fluid channels 142 are alternately disposed in the inner surface of the end ring to be spaced apart from each other in the circumferential direction, and the cooling fluid in the rotor core 133 can move in the same single direction along the axial fluid channels 135 and the second fluid channels 136 so as to implement the single-pass structure. Accordingly, the flow rate and the circulation flow rate of the cooling fluid can increase, thereby improving cooling performance of the rotor 130 and the stator 119 .
- FIG. 9 shows a graph and a table comparing example flow rates of a cooling fluid into the inlet of the rotary shaft of an electric motor with rotary fins and an electric motor without rotary fins.
- an electric motor of the present disclosure with the rotary fins 145 can have a cooling flow rate of 5.71 LPM at 1000 rpm and the cooling fluid is introduced into the inlet of the rotary shaft 131 .
- An electric motor 1 without the rotary fins 145 has a cooling flow rate of 1.25 LPM at 1000 rpm, and an electric motor of DENSO Cooperation without the rotary fins 145 has a cooling flow rate of 2.35 LPM at 1000 rpm.
- the electric motor of the present disclosure with the rotary fins 145 can have a cooling flow rate of 46.95 LPM at 5000 rpm and the cooling fluid is introduced into the inlet of the rotary shaft 131 .
- the electric motor 1 without the rotary fins 145 has a cooling flow rate of 9.82 LPM at 5000 rpm, and the electric motor of DENSO Cooperation without the rotary fins 145 has a cooling flow rate of 24.37 LPM at 5000 rpm.
- the electric motor of the present disclosure with the rotary fins 145 can have a cooling flow rate of 106.33 LPM at 10000 rpm and the cooling fluid is introduced into the inlet of the rotary shaft 131 .
- the electric motor 1 without the rotary fins 145 has a cooling flow rate of 21.99 LPM at 10000 rpm, and the electric motor of DENSO Corporation without the rotary fins 145 has a cooling flow rate of 49.97 LPM at 10000 rpm.
- the cooling flow rate of the electric motor 1 without the rotary fins 145 can be less than even 20% of that of the electric motor according to the present disclosure with the rotary fins 145 , and the electric motor of DENSO Corporation without the rotary fins 145 can be less than even 50% of that of the electric motor according to the present disclosure.
- the electric motor according to the present disclosure with the rotary fins 145 can provide remarkable effects compared to the electric motors of the related art.
- FIG. 10 is a conceptual view illustrating an example of a movement path of oil in accordance with another implementation of the present disclosure
- FIG. 11 is a conceptual view illustrating an example of first and second paths of a cooling fluid transferred from a rotary shaft to a rotor core of FIG. 2
- FIG. 12 is a conceptual view taken along the line XII-XII in FIG. 11 , which illustrates an example structure in which first and second paths of a cooling fluid transferred in both directions from the rotary shaft to the rotor core, respectively, are defined with a phase difference from each other in a circumferential direction.
- a plurality of communication holes 2311 and 2312 can be defined through a rotary shaft 231 in a spaced manner.
- This implementation can be different from the foregoing implementation illustrated in FIGS. 1 to 9 in that a cooling fluid transferred from the rotary shaft 231 to a rotor core through the plurality of communication holes flows axially in both directions opposite to each other.
- the plurality of communication holes 2311 and 2312 can include a plurality of first communication holes 2311 and a plurality of second communication holes 2312 .
- the first communication holes 2311 and the second communication holes 2312 can be spaced apart from each other in the axial direction.
- the plurality of first communication holes 2311 can be disposed adjacent to a first end ring, and the plurality of second communication holes 2312 can be disposed adjacent to a second end ring.
- the plurality of first communication holes 2311 and the plurality of second communication holes 2312 can be spaced apart from each other at equal intervals in a circumferential direction of the rotary shaft 231 .
- the plurality of first communication holes 2311 and the plurality of second communication holes 2312 can be alternately disposed in the axial direction with a preset phase difference in the circumferential direction of the rotary shaft 231 .
- a first path 2321 of a cooling fluid transmitted from the rotary shaft 231 to the rotor core through the plurality of first communication holes 2311 and a second path 2322 of a cooling fluid transmitted from the rotary shaft 231 to the rotor core through the plurality of second communication holes 2312 can be provided in the same number as the number of poles/2.
- the first paths 2321 and the second path 2 2322 can be alternately disposed in the axial direction with a phase difference of 360 degrees/the number of poles.
- Each of the first path 2321 and the second path 2322 has a single-pass fluid channel.
- each of the first path 2321 and the second path 2322 can be a pipe or tube.
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- Engineering & Computer Science (AREA)
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Abstract
Description
- Pursuant to 35 U.S.C. § 119(e), this application is a continuation of International Application PCT/KR2019/002266, with an international filing date of Feb. 25, 2019, the contents of which are hereby incorporated by reference herein in their entirety.
- The present disclosure relates to an electric motor that directly cools a shaft and a rotor using oil circulation.
- An electric vehicle may include an electric motor as a driving source for traveling the vehicle without exhaust gas.
- An electric motor (or motor) may include a rotor and a stator, and the rotor may be rotatably provided inside the stator.
- The stator may include a stator coil wound around a stator core. When current flows along the stator coil to rotate the rotor, heat may be generated in the stator coil.
- As for the electric motor used in the electric vehicle, cooling of heat generated in the electric motor may play an important role in achieving a smaller and more efficient electric motor.
- Motor cooling methods may include an indirect cooling method (water cooling) in which a channel for circulating cooling water is provided in a housing to indirectly cool a motor, and a direct cooling method (oil cooling) in which oil is sprayed onto a stator coil and the like to directly cool a motor.
- In some cases, the direct cooling method may have a high cooling efficiency and cooling performance, compared to the indirect cooling method using the cooling water.
- In some examples, a fluid channel through which oil flows may be provided in a shaft and a rotor core. As the oil flows along the fluid channel, the rotor core and permanent magnets may be cooled.
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FIG. 1 is a conceptual view illustrating a movement path of oil in an electric motor of the related art. - For example, an
oil channel 6 passing from arotor core 3 tomagnets 4 may be formed in therotor core 3 axially in both directions of ashaft 2, so that oil may be sprayed in the both directions throughend plates 5 mounted on both ends of therotor core 3. - The oil may be diverged and sprayed from the
rotor core 3 axially in the both directions opposite to each other. - For example, a circulation flow rate at which the oil flows along the
oil channel 6 may be slowed, and thereby the cooling performance of the oil may be deteriorated. - In some cases, after the oil introduced through an oil inlet of the
shaft 2 is filled in theoil channel 6 inside therotor core 3 by centrifugal force, when the oil is sprayed in the both directions throughcenter holes 7 formed through the bothend plates 5, respectively, the oil may be stagnated in theoil channel 6 formed between the twoend plates 5. - The present disclosure describes an electric motor that can increase a circulation flow rate of oil and improve cooling performance of a shaft and a rotor by using oil circulation.
- The present disclosure also describes an electric motor that can increase a circulation flow rate of oil flowing along a fluid channel defined inside a shaft and a rotor core by fast rotating air around end plates to lower pressure of the air.
- According to one aspect of the subject matter described in this application, a rotor includes a rotary shaft defining a first fluid channel configured to guide a cooling fluid, a rotor core that is configured to rotate about the rotary shaft, that includes a plurality of permanent magnets, and that defines a plurality of second fluid channels that are in fluid communication with the first fluid channel and configured to cool the plurality of permanent magnets by the cooling fluid, and a plurality of end rings that are respectively disposed at end portions of the rotor core and that define a plurality of spray holes that are in fluid communication with the plurality of second fluid channels and configured to spray the cooling fluid to an outside of the rotor core. Each end ring among the plurality of end rings includes a plurality of rotary fins that are disposed on an outer surface of the end ring and spaced apart from one another in a circumferential direction, where the plurality of rotary fins are configured to circulate, to the first fluid channel, the cooling fluid sprayed through the plurality of spray holes.
- Implementations according to this aspect can include one or more of the following features. For example, each fin of the plurality of rotary fins can protrude from the outer surface of the end ring in an axial direction of the rotary shaft and has a curved shape that is curved from an inner end portion of the end ring to an outer end portion of the end ring in a radial direction, where the plurality of rotary fins are configured to cause air to rotate around the end ring. In some examples, the plurality of end rings can include a first end ring disposed at a first end portion of the rotor core and a second end ring disposed at a second end portion of the rotor core, where the second end portion is spaced apart from the first end portion in an axial direction of the rotary shaft. The first end ring and the second end ring can be asymmetric with each other.
- In some implementations, the first end ring can include a plurality of first rotary fins, and the second end ring can include a plurality of second rotary fins, where the plurality of first rotary fins and the plurality of second rotary fins are curved in a rotating direction of the rotor core. In some examples, each of the first end ring and the second end ring can define (i) a plurality of injection fluid channels that are disposed at an inner surface of one of the first end ring and the second end ring, the inner surface facing an end of the rotor core, where the plurality of injection fluid channels are spaced apart from one another in the circumferential direction and in fluid communication with the plurality of spray holes, and (ii) a plurality of return fluid channels that are arranged alternately with the plurality of injection fluid channels in the circumferential direction, where the plurality of return fluid channels are configured to transfer the cooling fluid from the rotor core toward another end of the rotor core in the axial direction.
- In some examples, the rotor core can further define a plurality of axial fluid channels that extend from a radially inner end portion of the rotor core, where the plurality of axial fluid channels are connected to and in fluid communication with the first fluid channel, and each of the plurality of return fluid channels can include a connection fluid channel that is connected to and in fluid communication with one of the plurality of axial fluid channels.
- In some implementations, the cooling fluid can be oil.
- In some implementations, each of the plurality of spray holes can be inclined with respect to an axial direction of the rotary shaft and extends toward an outside of one of the plurality of end rings. In some examples, each of the plurality of injection fluid channels of the first end ring can face one of the plurality of return fluid channels of the second end ring in the axial direction. In some examples, the rotor core and the plurality of permanent magnets can be configured to be cooled by the cooling fluid moving from the first fluid channel to the plurality of second fluid channels. The plurality of spray holes can be configured to spray the cooling fluid to a stator coil disposed outside the rotor core to thereby cool the stator coil.
- In some examples, the rotor can include a plurality of paths configured to transfer the cooling fluid from the rotary shaft to the rotor core, where a number of the plurality of paths is equal to a number of poles of the plurality of permanent magnets. The rotary shaft can further define a plurality of communication holes that are connected to the rotor core, that are defined at a middle portion of the rotary shaft, and that extend in a radial direction of the rotary shaft.
- In some examples, the rotor can further include a plurality of paths configured to transfer the cooling fluid from the rotary shaft to the rotor core, where a number of the plurality of paths is a half of a number of poles of the plurality of permanent magnets. The rotary shaft can further define a plurality of communication holes that are connected to the rotor core, that are defined through a first end portion and a second end portion of the rotary shaft, and that extend in a radial direction of the rotary shaft.
- In some examples, the plurality of communication holes can include a plurality of first communication holes defined through the first end portion of the rotary shaft, and a plurality of second communication holes defined through the second end portion of the rotary shaft, where each of the plurality of first communication holes is spaced apart from one of the plurality of second communication holes in the circumferential direction by a preset angle.
- According to another aspect, an electric motor includes a housing, a stator that is disposed in the housing and includes a stator core and a stator coil wound around the stator core, a rotor including a rotary shaft, a rotor core disposed in the stator and configured to rotate about the rotary shaft, and a plurality of permanent magnets disposed at the rotor core, and a plurality of end rings respectively disposed at ends of the rotor core. The housing defines a plurality of spray nozzles therein that are configured to spray a cooling fluid to the stator coil and the stator core. The rotor defines a first fluid channel inside the rotary shaft, a plurality of second fluid channels inside the rotor core, where the plurality of second fluid channel are in contact with the plurality of permanent magnets, and a plurality of spray holes that are connected to and in fluid communication with the plurality of second fluid channels, where the plurality of spray holes extend obliquely through an outer circumferential portion of one of the plurality of end rings and are configured to spray the cooling fluid to an end portion of the stator coil. The first fluid channel, the plurality of second fluid channels, and the plurality of spray holes define a single-pass structure configured to guide the cooling fluid in a single direction.
- Implementations according to this aspect can include one or more of the following features. For example, each end ring among the plurality of end rings can include a plurality of rotary fins that protrude from an outer surface of the end ring and that have a curved shape, where the plurality of rotary fins are configured to circulate, to the first fluid channel, the cooling fluid sprayed from the plurality of spray nozzles and the plurality of spray holes. In some examples, the plurality of end rings can include a first end ring and a second end ring that are spaced apart from each other in the single direction. In some examples, the plurality of second fluid channels are spaced apart from one another and extend parallel to the single direction.
- In some implementations, the rotary shaft can further define a plurality of communication holes that are connected to the rotor core and extend in a radial direction of the rotary shaft. In some examples, the plurality of communication holes can include a plurality of first communication holes defined at a first end portion of the rotary shaft, and a plurality of second communication holes defined at a second end portion of the rotary shaft, where each of the plurality of first communication holes is spaced apart from one of the plurality of second communication holes in a circumferential direction of the rotary shaft by a preset angle.
- In some implementations, the electric motor can include a plurality of first pipes that extend from the plurality of first communication holes to the rotor core, and a plurality of second pipes that extend from the plurality of second communication holes to the rotor core, where a length of each of the plurality of first pipes is different from a length of each of the plurality of second pipes.
- In some implementations, a plurality of rotary fins can protrude from an outer surface of each end ring in a curved shape along a circumferential direction. As the plurality of rotary fins rotate together with a rotor core, air around spray holes of the end ring can flow rapidly, which can cause a pressure drop. Accordingly, a cooling fluid can flow from a first fluid channel of a rotary shaft into axial fluid channels and second fluid channels of the rotor core so as to be sprayed onto an inner circumferential surface of an end turn of a stator through a plurality of spray holes.
- In some implementations, the plurality of rotary fins can provide circulating power to the cooling fluid, so that the cooling fluid can move from the first fluid channel of the rotary shaft into the axial fluid channels and second fluid channels of the rotor core and easily circulate back to the first fluid channel of the rotary shaft through spray holes of the end ring, thereby increasing a circulation flow rate of the cooling fluid.
- In some implementations, since a rotation speed of the plurality of rotary fins increases according to the rotation of the rotor core, a flow rate of the cooling fluid introduced into the rotary shaft can increase.
- In some implementations, since the plurality of rotary fins are disposed on each of a first end ring and a second end ring to be curved in the same direction as a rotating direction of the rotor core, circulating power of the cooling fluid can further be doubled.
- In some implementations, as paths along which the cooling fluid is transferred from the rotary shaft to the rotor core are independently defined in the same number as the number of poles, the cooling fluid can flow along each of a plurality of permanent magnets so as to uniformly cool down the permanent magnets for each polarity.
- In some implementations, a plurality of injection fluid channels and a plurality of return fluid channels can be alternately disposed in an inner surface of the end ring in a spaced manner along a circumferential direction, and the cooling fluid in the rotor core can move in the same single direction along the axial fluid channels and the second fluid channels so as to implement a single-pass structure. Accordingly, a flow rate and a circulation flow rate of the cooling fluid can increase, thereby improving cooling performance of the rotor and the stator.
-
FIG. 1 is a conceptual view illustrating a movement path of oil in an electric motor of related art. -
FIG. 2 is a cross-sectional view illustrating an internal structure of an example electric motor. -
FIG. 3 is a conceptual view illustrating an example rotor ofFIG. 2 . -
FIG. 4 is a conceptual view illustrating example end rings mounted to both ends of a rotor core inFIG. 3 . -
FIG. 5 is a conceptual view illustrating an example structure including a plurality of injection fluid channels and a plurality of return fluid channels that are alternately defined through each end ring inFIG. 4 . -
FIG. 6 is a cross-sectional view taken along the line VI-VI ofFIG. 3 . -
FIG. 7 is a cross-sectional view taken along the line VII-VII ofFIG. 6 . -
FIG. 8 is a conceptual view illustrating an example of a movement path of oil. -
FIG. 9 shows a graph and a table comparing example flow rates of a cooling fluid into an inlet of a rotary shaft of an example electric motor with rotary fins and an electric motor without rotary fins. -
FIG. 10 is a conceptual view illustrating another example of a movement path of oil. -
FIG. 11 is a conceptual view illustrating an example of first and second paths of a cooling fluid transferred from a rotary shaft to a rotor core ofFIG. 2 . -
FIG. 12 is a conceptual view taken along the line XII-XII inFIG. 11 illustrating an example structure in which first and second paths of a cooling fluid transferred in both directions from the rotary shaft to the rotor core, respectively, are defined with a phase difference from each other in a circumferential direction. - Description will now be given in detail according to exemplary implementations disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components can be provided with the same or similar reference numbers, and description thereof will not be repeated.
-
FIG. 2 is a cross-sectional view illustrating an internal structure of an example electric motor,FIG. 3 is a conceptual view illustrating anexample rotor 130 ofFIG. 2 , andFIG. 4 is a conceptual view illustrating example end rings mounted to both ends of arotor core 133 inFIG. 3 .FIG. 5 is a conceptual view illustrating an example structure in which a plurality ofinjection fluid channels 141 and a plurality ofreturn fluid channels 142 are alternately defined through each end ring inFIG. 4 ,FIG. 6 is a cross-sectional view taken along the line VI-VI ofFIG. 3 ,FIG. 7 is a cross-sectional view taken along the line VII-VII ofFIG. 6 , andFIG. 8 is a conceptual view illustrating an example of a movement path of oil in accordance with the present disclosure. - In some implementations, an electric motor can include a
housing 100, a housing cover, astator 119, and arotor 130. - The
housing 100 can have a cylindrical shape. An accommodation space can be defined inside thehousing 100. Thestator 119 and therotor 130 can be accommodated in thehousing 100. - The housing cover can be provided on both ends of the
housing 100 in a lengthwise direction to cover both end portions of thehousing 100. The housing cover can include afirst housing cover 115 disposed on one end of thehousing 100 and asecond housing cover 117 disposed on another end of thehousing 100. - A cooling
fluid channel 110 in which a cooling fluid such as oil flows can be defined in thehousing 100. An inlet can be defined through an upper portion of thehousing 100, so that the cooling fluid can be injected into thehousing 100. - A plurality of spray nozzles (or injection nozzles) can be defined through the inside of the
housing 100 in a thickness direction. - The plurality of spray nozzles can be spaced apart from one another in a lengthwise direction of the
housing 100. One side of each of the plurality of spray nozzles can communicate with the coolingfluid channel 110 and another side of each of the plurality of spray nozzles can communicate with the accommodation space of thehousing 100. - The plurality of spray nozzles can be defined perpendicularly downward or can be inclined. Some of the plurality of spray nozzles can be defined horizontally.
-
First spray nozzles 111 defined horizontally among the plurality of spray nozzles can spray oil into the accommodation space toward thefirst housing cover 115, andsecond spray nozzles 112 defined to be inclined among the plurality of spray nozzles can spray oil into the accommodation space toward abearing 118. -
Third spray nozzles 113 defined perpendicularly downward among the plurality of spray nozzles can spray oil into the accommodation space toward an outer circumferential portion of anend turn 122 of thestator coil 121, andfourth spray nozzles 114 defined perpendicularly downward among the plurality of spray nozzles can spray oil into the accommodation space toward thestator core 120. - With this configuration, a cooling fluid such as oil can be sprayed onto the
stator coil 121, thestator core 120, and thebearing 118 to cool thestator coil 121, thestator core 120, and thebearing 118. - A
cover fluid channel 116 can be defined in thefirst housing cover 115. One side of thecover fluid channel 116 can communicate with an accommodation hole in which oil sprayed from thefirst spray nozzles 111, and a middle portion of thecover fluid channel 116 can communicate with an inside of one end portion of therotary shaft 131. - With this configuration, the oil injected from the
first spray nozzles 111 can be sprayed into thecover fluid channel 116 through the accommodation hole, and the oil flowing along thecover fluid channel 116 can flow into the one end portion of therotary shaft 131. - The
stator 119 can include astator core 120 and astator coil 121. Thestator core 120 can include a plurality of electrical steel sheets that are stacked. A rotor accommodation hole for accommodating therotor 130 can be defined in a radial center of thestator core 120. - A plurality of slots and a plurality of teeth can be alternately disposed at an inner side of the stator core 12 in a circumferential direction. The plurality of slots can be defined through the
stator core 120 in an axial direction. - The
stator coil 121 can be configured as a hairpin type. The plurality of stator coils 121 can be wound around thestator core 120 through the plurality of slots. End turns 122 that protrude from the slots to the outside of thestator core 120 can be disposed at both end portions of thestator coil 121, respectively. - The end turns 122 can be bent from the
stator coil 121 at a preset angle and extend to an opposite side in a lengthwise direction of thestator core 120. - The
rotor 130 can include arotary shaft 131, arotor core 133,permanent magnets 137, and end rings. - The
rotary shaft 131 can have a firstfluid channel 132 therein, such that a cooling fluid flows along the firstfluid channel 132. The firstfluid channel 132 can extend in the axial direction. A plurality ofcommunication holes 1310 can be defined through one side of therotary shaft 131 in the radial direction. - The plurality of
communication holes 1310 can be configured to transfer the cooling fluid flowing along the firstfluid channel 132 into therotor core 133. The plurality ofcommunication holes 1310 can be disposed on therotary shaft 131 to be spaced apart from one another in the circumferential direction. The plurality ofcommunication holes 1310 can be disposed on a central portion of therotary shaft 131 in a lengthwise direction of therotary shaft 131. - The
rotor core 133 can be mounted to therotary shaft 131 to be rotatable together with therotary shaft 131. Therotor core 133 can have a cylindrical shape. Therotor core 133 can include a plurality of electrical steel sheets that are stacked. - A rotary shaft accommodation hole for accommodating the
rotary shaft 131 can be defined through the center of therotor core 133 in the axial direction. - A plurality of permanent magnet accommodation holes for accommodating a plurality of
permanent magnets 137 can be defined in therotor core 133. - A plurality of axial
fluid channels 135 and a plurality of secondfluid channels 136 through which the cooling fluid flows can be defined in therotor core 133. - The plurality of axial
fluid channels 135 can be defined in an inner end portion of therotor core 133 in the radial direction. The plurality of axialfluid channels 135 can be spaced apart from one another in the circumferential direction. Each of the plurality of axialfluid channels 135 can extend along the axial direction of therotor core 133. - The plurality of axial
fluid channels 135 can communicate with the plurality ofcommunication holes 1310, such that the cooling fluid can move from therotary shaft 131 to therotor core 133 through the plurality of communication holes 1310. Accordingly, the cooling fluid can directly cool down therotor core 133 through heat exchange with therotor core 133. - The plurality of second
fluid channels 136 can surround thepermanent magnets 137 such that the cooling fluid can be brought into contact with at least parts or portions of thepermanent magnets 137 so as to cool down thepermanent magnets 137 through heat conduction from thepermanent magnets 137. - The plurality of second
fluid channels 136 can be defined in an outer end portion of therotor core 133 in the radial direction. The plurality of secondfluid channels 136 can be spaced apart from one another in the circumferential direction. Each of the plurality of secondfluid channels 136 can extend in a lengthwise direction of therotor core 133. - The plurality of second
fluid channels 136 can be parallel to the plurality of axialfluid channels 135. However, the plurality of secondfluid channels 136 can be connected respectively to the plurality of axialfluid channels 135 by inner fluid channels defined in an inner surface of the end ring. The plurality of secondfluid channels 136 can be arranged in parallel, for example, in two rows. - With this configuration, the cooling fluid can flow from the axial
fluid channels 135 into the secondfluid channels 136 to be brought into contact with thepermanent magnets 137, thereby cooling down thepermanent magnets 137 through heat exchange with thepermanent magnets 137. - The end rings can be coupled to cover both ends of the
rotor core 133, and can be mounted to therotary shaft 131 to be rotatable together with therotary shaft 131. A rotary shaft accommodation hole can be defined through a center of each end ring. - A plurality of spray holes (or injection holes) 140 can be defined through an outer circumferential portion of the end ring in a thickness direction. Each of the plurality of
spray holes 140 can communicate with the plurality of secondfluid channels 136. The plurality ofspray holes 140 can be spaced apart from one another in a circumferential direction of the end ring. - With this configuration, the cooling fluid can be sprayed from the
rotor core 133 into the accommodation space of thehousing 100 through the plurality of spray holes 140. - Each of the plurality of
spray holes 140 can be disposed at an inner side of the outer circumferential portion of each end ring to be inclined toward an inner circumferential surface of theend turn 122 of thestator coil 121. - With this configuration, the cooling fluid can be sprayed on the inner circumferential surface of the
end turn 122 of thestator coil 121 through the plurality of spray holes 140. Accordingly, a contact area of thestator coil 121 with the cooling fluid can be further expanded to the inner circumferential surface as well as the outer circumferential surface of theend turn 122, thereby further improving the cooling performance by taking more heat from thestator coil 121. - A plurality of
rotary fins 145 can protrude from an outer surface of each end ring in the axial direction, so as to rotate air around the end ring. Each of the plurality ofrotary fins 145 can rotate together with therotor core 133 centering on therotary shaft 131. - Each of the plurality of
rotary fins 145 can be disposed to be spaced apart from one another in the circumferential direction. Each of the plurality ofrotary fins 145 can have a curved shape. Each of the plurality ofrotary fins 145 can have an arcuate shape. The plurality ofrotary fins 145 can be bent in the same direction as a rotating direction of therotor core 133. - Outer end portions of the
rotary fins 145 in the radial direction can be disposed adjacent to an outer circumferential portion of the end ring, and inner end portions of therotary fins 145 can be disposed adjacent to the rotary shaft accommodation hole of the end ring. An interval between the outer end portions of the plurality ofrotary fins 145 adjacent to each other in the circumferential direction can be wider than an interval between the inner end portions of the plurality ofrotary fins 145 adjacent to each other in the circumferential direction. - With this configuration, the outer end portions of the
rotary fins 145 can be disposed adjacent to the spray holes 140, such that air around an outer side of the spray holes 140 can be quickly moved. Accordingly, pressure can be lowered at the outer side of the spray holes 140, which can facilitate circulation of the cooling fluid. - For example, when the pressure at the outer side of the spray holes 140 is lowered, internal pressure of the
rotor core 133 can be relatively increased, which can facilitate the cooling fluid to be sprayed from the inside of therotor core 133 through the spray holes 140. - A plurality of
injection fluid channels 141 and a plurality ofreturn fluid channels 142 can be disposed in an inner surface of each end ring. - The plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 can be alternately spaced apart from each other in the circumferential direction of the end ring. Each of the plurality ofinjection fluid channels 141 and the plurality ofreturn fluid channels 142 can be recessed in the inner surface of each end ring in the thickness direction. - The plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 can be defined to correspond to an arrangement shape of thepermanent magnets 137. - For example, the plurality of
permanent magnets 137 can have a plate shape and can be arranged in an inverted triangle shape. - The plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 can be defined in an inverted triangular shape. - The plurality of
injection fluid channels 141 can communicate with the plurality ofspray holes 140, respectively. Each of the plurality ofinjection fluid channels 141 can be configured to connect the secondfluid channel 136 and thespray hole 140. The plurality ofspray holes 140 can be disposed on an outer surface of each of the plurality ofinjection fluid channels 141 to be spaced apart from each other in the circumferential direction. - With this configuration, the plurality of
injection fluid channels 141 can temporarily collect and store the cooling fluid delivered from the secondfluid channels 136 and distribute the cooling fluid into the plurality of spray holes 140. The distributed cooling fluid can then be sprayed onto theend turn 122 through the plurality of spray holes 140. - The plurality of
return fluid channels 142 can change a flowing direction of the cooling fluid transferred from the axialfluid channels 135 to return to the secondfluid channels 136. - Each of the plurality of
return fluid channels 142 can be provided with aconnection fluid channel 143 at an inner side of the end ring in the radial direction. One side of theconnection fluid channel 143 can communicate with the secondfluid channel 136 and another side of theconnection fluid channel 143 can communicate with theaxial fluid channel 135, such that the secondfluid channel 136 and theaxial fluid channel 135 can be connected to each other. - The
rotor core 133 can include a plurality of weight-reducingholes 134 disposed between the permanent magnet accommodation holes and the rotary shaft accommodation hole. The plurality of weight-reducingholes 134 can extend along the lengthwise direction of therotor core 133. The plurality of weight-reducingholes 134 can be spaced apart from the permanent magnet accommodation holes with a preset phase difference 8 in the circumferential direction. - A plurality of weight-reducing
grooves 144 can be defined at the inner surface of each end ring. The plurality of weight-reducinggrooves 144 can have a shape corresponding to the plurality of weight-reducingholes 134 so as to communicate with the plurality of weight-reducingholes 134 in an overlapping manner along the axial direction. - The
connection fluid channel 143 can communicate with the weight-reducinggroove 144. One side of theconnection fluid channel 143 can connect the secondfluid channel 136 and the weight-reducinggroove 144, and another side of theconnection fluid channel 143 can connect the weight-reducinggroove 144 and theaxial fluid channel 135. - With this configuration, the plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 can be alternately arranged in the circumferential direction, so that the cooling fluid can be transferred from therotary shaft 131 to therotor core 133 through a single-pass structure. - For example, the single-pass structure means that the cooling fluid passes only once along the same path (or direction) through the axial
fluid channels 135 and the secondfluid channels 136, which are the inner fluid channels of therotor core 133, from therotary shaft 131. - Hereinafter, the single-pass structure of the
rotor core 133 and the end ring will be described with reference toFIG. 8 . - Front and rear end portions of the
rotary shaft 131 can be rotatably supported bybearings 118. Thebearings 118 can be mounted to thefirst housing cover 115 and thesecond housing cover 117. A sealing cover can be mounted on thefirst housing cover 115, to seal a gap between thefirst housing cover 115 and the firstfluid channel 132 of therotary shaft 131. - The end rings can include a
first end ring 138 disposed on one end of therotor core 133 facing thefirst housing cover 115 in the axial direction, and asecond end ring 139 disposed on another end of therotor core 133 facing thesecond housing cover 117 in the axial direction. - In order to implement the single-pass structure, the
first end ring 138 and thesecond end ring 139 can be asymmetric to each other. - An outer surface of the
first end ring 138 and an outer surface of thesecond end ring 139 can be disposed to face opposite directions. Firstrotary fins 1451 disposed on the outer surface of thefirst end ring 138 and secondrotary fins 1452 disposed on the outer surface of thesecond end ring 139 can be curved in the same direction as the rotating direction of therotor core 133. - For example, when the
first end ring 138 is viewed from thefirst housing cover 115 in the axial direction, the firstrotary fins 1451 can be curved clockwise and rightward from inside to outside in the radial direction. When thesecond end ring 139 is viewed from thesecond housing cover 117 in the axial direction, the secondrotary fins 1452 can be curved counterclockwise and leftward from the inside to the outside in the radial direction. - The plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 defined in the inner surface of thefirst end ring 138 and the plurality ofinjection fluid channels 141 and the plurality ofreturn fluid channels 142 defined in the inner surface of thesecond end ring 139 can be disposed in an alternating manner in the axial direction with a preset phase difference in the circumferential direction. - That is, the
injection fluid channel 141 of thefirst end ring 138 and thereturn fluid channel 142 of thesecond end ring 139 can be disposed to face each other in the axial direction, and theinjection fluid channel 141 of thefirst end ring 138 and theinjection fluid channel 141 of thesecond end ring 139 can be alternately arranged in the axial direction. - Hereinafter, a movement path of a cooling fluid will be described.
- An inlet can be defined from one end portion of the
rotary shaft 131 to be opened. Accordingly, a cooling fluid such as oil can be introduced into the firstfluid channel 132 through the inlet of therotary shaft 131. The cooling fluid can be air. - The cooling fluid can cool the
rotary shaft 131 through heat exchange with therotary shaft 131 while flowing along the firstfluid channel 132 of therotary shaft 131. - The cooling fluid can be delivered to the
rotor core 133 through thecommunication hole 1310 connecting therotary shaft 131 and therotor core 133. At this time, the number of paths along which the cooling fluid is transferred from therotary shaft 131 to therotor core 133 can be the same as the number of poles of the electric motor. - For example, in some implementations, the electric motor can have 6 poles, and six paths of the cooling fluid transmitted from the
rotary shaft 131 to therotor core 133 through thecommunication holes 1310 can be defined. - The cooling fluid can be introduced into the
first end ring 138 along the axialfluid channels 135 extending toward thefirst end ring 138 in the axial direction. - The
connection fluid channels 143 connecting thefirst end ring 138 and therotor core 133 can be defined in the inner surface of thefirst end ring 138 and extend radially to communicate with the axialfluid channels 135. The cooling fluid can be introduced into the weight-reducinggrooves 144 through theconnection fluid channels 143 via the axialfluid channels 135, temporarily stay in the weight-reducinggrooves 144, and then flow to thereturn fluid channels 142 through theconnection fluid channels 143 again. - The
return fluid channels 142 can communicate with the secondfluid channels 136 and switch a flowing direction of the cooling fluid such that the cooling fluid can flow from thefirst end ring 138 to thesecond end ring 139 in the axial direction. - The second
fluid channels 136 can communicate with the permanent magnet accommodation holes. The secondfluid channels 136 can be arranged in parallel in two rows at an outer side and an inner side of therotor core 133 in the radial direction of therotor core 133. - The cooling fluid can be introduced into the permanent magnet accommodation holes while flowing along the second
fluid channels 136, so as to cool down thepermanent magnets 137 through heat exchange with thepermanent magnets 137. - The cooling fluid can flow onto an inner surface of the
second end ring 139 through theinjection fluid channel 141 that connects therotor core 133 and thesecond end ring 139 and faces thereturn fluid channel 142 of thefirst end ring 138 in the axial direction. - The cooling fluid can be sprayed from the
second end ring 139 into the accommodation space of thehousing 100 through the plurality ofspray holes 140 defined through theinjection fluid channel 141. At this time, the cooling fluid can be sprayed onto an inner circumferential surface of theend turn 122 through the plurality ofspray holes 140, thereby cooling down thestator coil 121 through heat exchange with theend turn 122. - The cooling fluid sprayed from the
second end ring 139 can flow back into therotary shaft 131 and circulate. - Here, the cooling fluid can be transferred from the
rotary shaft 131 to therotor core 133. The cooling fluid inside therotor core 133 can flow in the same single direction, that is, from thefirst end ring 138 to thesecond end ring 139 along the secondfluid channels 136, and be sprayed onto the inner circumferential surface of theend turn 122, which protrudes from one end portion of thestator core 120 in the lengthwise direction, through the spray holes 140 of thesecond end ring 139. Thus, the cooling fluid can flow through a single-pass structure. - When the number of poles of the electric motor is 6, the number of paths that the cooling fluid is transmitted from the
rotary shaft 131 to therotor core 133 can be 6 paths, and the cooling fluid can radially move in therotor core 133 independently for each polarity and move in a single pass for each polarity. - However, a moving direction of the cooling fluid in the
rotor core 133 can change from thefirst end ring 138 to thesecond end ring 139 or from thesecond end ring 139 to thefirst end ring 138 in an alternating manner whenever a position changes to an adjacent polarity in a circumferential direction. - Therefore, in some implementations, the plurality of
rotary fins 145 can protrude from the outer surface of each end ring to be curved in the circumferential direction. As the plurality ofrotary fins 145 rotate together with therotor core 133, air around the spray holes 140 of the end ring can flow fast to cause a pressure drop. Accordingly, the cooling fluid can flow from the firstfluid channel 132 of therotary shaft 131 to the axialfluid channels 135 and the secondfluid channels 136 of therotor core 133 so as to be sprayed onto the inner circumferential surface of theend turn 122 of thestator 119 through the plurality of spray holes 140. - As the plurality of
rotary fins 145 provide circulating power to the cooling fluid, the cooling fluid can move from the firstfluid channel 132 of therotary shaft 131 to the axialfluid channels 135 and the secondfluid channels 136 of therotor core 133, so as to easily circulate from the spray holes 140 of the end ring back to the firstfluid channel 132 of therotary shaft 131, thereby increasing a circulation flow rate of the cooling fluid. - In some examples, since a rotation speed of the plurality of
rotary fins 145 increases according to the rotation of therotor core 133, a flow rate of the cooling fluid flowing into therotary shaft 131 can increase. - In addition, since the plurality of
rotary fins 145 are disposed on each of thefirst end ring 138 and thesecond end ring 139 to be curved in the same direction as the rotating direction of therotor core 133, circulating power of the cooling fluid can be further doubled. - Further, as the paths along which the cooling fluid is transmitted from the
rotary shaft 131 to therotor core 133 are independently defined in the same number as the number of poles, the cooling fluid can flow to each of the plurality ofpermanent magnets 137, so as to uniformly cool down thepermanent magnets 137 for each polarity. - Furthermore, the plurality of
injection fluid channels 141 and the plurality ofreturn fluid channels 142 are alternately disposed in the inner surface of the end ring to be spaced apart from each other in the circumferential direction, and the cooling fluid in therotor core 133 can move in the same single direction along the axialfluid channels 135 and the secondfluid channels 136 so as to implement the single-pass structure. Accordingly, the flow rate and the circulation flow rate of the cooling fluid can increase, thereby improving cooling performance of therotor 130 and thestator 119. -
FIG. 9 shows a graph and a table comparing example flow rates of a cooling fluid into the inlet of the rotary shaft of an electric motor with rotary fins and an electric motor without rotary fins. - For example, an electric motor of the present disclosure with the
rotary fins 145 can have a cooling flow rate of 5.71 LPM at 1000 rpm and the cooling fluid is introduced into the inlet of therotary shaft 131. An electric motor 1 without therotary fins 145 has a cooling flow rate of 1.25 LPM at 1000 rpm, and an electric motor of DENSO Cooperation without therotary fins 145 has a cooling flow rate of 2.35 LPM at 1000 rpm. - The electric motor of the present disclosure with the
rotary fins 145 can have a cooling flow rate of 46.95 LPM at 5000 rpm and the cooling fluid is introduced into the inlet of therotary shaft 131. The electric motor 1 without therotary fins 145 has a cooling flow rate of 9.82 LPM at 5000 rpm, and the electric motor of DENSO Cooperation without therotary fins 145 has a cooling flow rate of 24.37 LPM at 5000 rpm. - The electric motor of the present disclosure with the
rotary fins 145 can have a cooling flow rate of 106.33 LPM at 10000 rpm and the cooling fluid is introduced into the inlet of therotary shaft 131. The electric motor 1 without therotary fins 145 has a cooling flow rate of 21.99 LPM at 10000 rpm, and the electric motor of DENSO Corporation without therotary fins 145 has a cooling flow rate of 49.97 LPM at 10000 rpm. - In some cases, the cooling flow rate of the electric motor 1 without the
rotary fins 145 can be less than even 20% of that of the electric motor according to the present disclosure with therotary fins 145, and the electric motor of DENSO Corporation without therotary fins 145 can be less than even 50% of that of the electric motor according to the present disclosure. The electric motor according to the present disclosure with therotary fins 145 can provide remarkable effects compared to the electric motors of the related art. -
FIG. 10 is a conceptual view illustrating an example of a movement path of oil in accordance with another implementation of the present disclosure,FIG. 11 is a conceptual view illustrating an example of first and second paths of a cooling fluid transferred from a rotary shaft to a rotor core ofFIG. 2 , andFIG. 12 is a conceptual view taken along the line XII-XII inFIG. 11 , which illustrates an example structure in which first and second paths of a cooling fluid transferred in both directions from the rotary shaft to the rotor core, respectively, are defined with a phase difference from each other in a circumferential direction. - In some implementations, a plurality of
communication holes rotary shaft 231 in a spaced manner. This implementation can be different from the foregoing implementation illustrated inFIGS. 1 to 9 in that a cooling fluid transferred from therotary shaft 231 to a rotor core through the plurality of communication holes flows axially in both directions opposite to each other. - The plurality of
communication holes first communication holes 2311 and a plurality of second communication holes 2312. Thefirst communication holes 2311 and thesecond communication holes 2312 can be spaced apart from each other in the axial direction. - The plurality of
first communication holes 2311 can be disposed adjacent to a first end ring, and the plurality ofsecond communication holes 2312 can be disposed adjacent to a second end ring. - The plurality of
first communication holes 2311 and the plurality ofsecond communication holes 2312 can be spaced apart from each other at equal intervals in a circumferential direction of therotary shaft 231. - The plurality of
first communication holes 2311 and the plurality ofsecond communication holes 2312 can be alternately disposed in the axial direction with a preset phase difference in the circumferential direction of therotary shaft 231. - A
first path 2321 of a cooling fluid transmitted from therotary shaft 231 to the rotor core through the plurality offirst communication holes 2311 and asecond path 2322 of a cooling fluid transmitted from therotary shaft 231 to the rotor core through the plurality ofsecond communication holes 2312 can be provided in the same number as the number of poles/2. - The
first paths 2321 and thesecond path 2 2322 can be alternately disposed in the axial direction with a phase difference of 360 degrees/the number of poles. - Each of the
first path 2321 and thesecond path 2322 has a single-pass fluid channel. For example, each of thefirst path 2321 and thesecond path 2322 can be a pipe or tube. - Since other components are the same as or similar to those in the foregoing implementation of
FIGS. 1 to 9 , a duplicated description will be omitted.
Claims (20)
Applications Claiming Priority (1)
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PCT/KR2019/002266 WO2020175715A1 (en) | 2019-02-25 | 2019-02-25 | Rotor and electric motor including same |
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PCT/KR2019/002266 Continuation WO2020175715A1 (en) | 2019-02-25 | 2019-02-25 | Rotor and electric motor including same |
Publications (1)
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US20210384801A1 true US20210384801A1 (en) | 2021-12-09 |
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US17/411,358 Pending US20210384801A1 (en) | 2019-02-25 | 2021-08-25 | Rotor and electric motor including same |
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US (1) | US20210384801A1 (en) |
EP (1) | EP3934065A4 (en) |
CN (1) | CN113519107B (en) |
WO (1) | WO2020175715A1 (en) |
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US20230093220A1 (en) * | 2021-09-21 | 2023-03-23 | Dana Automotive Systems Group, Llc | Electric motor with water jacket and oil-cooled stator and method for operation of the electric motor |
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FR3116964A1 (en) * | 2020-11-30 | 2022-06-03 | Nidec Psa Emotors | Flange and rotor of rotating electric machine |
FR3116962A1 (en) * | 2020-11-30 | 2022-06-03 | Nidec Psa Emotors | Flange and rotor of rotating electric machine |
DE102022112735A1 (en) * | 2022-05-20 | 2023-11-23 | Rheinmetall Air Defence Ag | Revolver gun and method for operating a revolver gun |
FR3141015A1 (en) | 2022-10-17 | 2024-04-19 | Nidec Psa Emotors | Electric machine rotor flange |
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Also Published As
Publication number | Publication date |
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CN113519107B (en) | 2023-12-26 |
EP3934065A1 (en) | 2022-01-05 |
WO2020175715A1 (en) | 2020-09-03 |
EP3934065A4 (en) | 2022-10-19 |
CN113519107A (en) | 2021-10-19 |
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